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Komodo Dragon (Varanus komodoensis) Fact Sheet: Physical Characteristics

Komodo Dragon (Varanus komodoensis)

Physical Characteristics

Body measurements

AttributeMalesFemales
Weight up to 90 kg (198 lb) up to 70 kg (154 kg)
Length 3 m (10 ft) 2 m (6.6 ft)

General Appearance

Body size

  • Largest living lizard
  • Head raised to full extent is approximately 40 cm above the ground.
    • When head is lowered, the animal is less than 20 cm high (Long neck can stretch to give the dragon a better view of its surroundings in tall grass.
  • Males are bulkier and larger than females.
  • Juvenile Komodos are slender and agile. Adults are massive with flatter bodies and proportionately shorter tails

Traits

  • Toes have sharp, recurved claws.
  • Teeth are specialized for a carnivorous diet.
    • They are serrated, compressed laterally, and curved posteriorly with a sharp tip and broad base, (Curved teeth are better than straight teeth for catching and holding prey).
    • Although many varanids have one or two replacement teeth at each position, the Komodo has four or five. Longest teeth are approximately 2 cm.
  • Venom toxins are now known to be present in toxin-secreting glands of monitor lizards (Fry et al. 2006; Fry et al. 2009)
    • Biologists hypothesize that venom systems evolved early in the evolution of both snakes and lizards
    • Nine toxin types are shared between lizards and snakes
    • In one monitor lizard, the Lace Monitor (Varanus varius), its toxin effects blood pressure and clotting ability of its prey
  • Short intestine is typical of carnivores (Diets high in proteins and lipids don't require a great deal of digestive processing)
  • Skin is like "chain-mail" with numerous osteoderms.
    • Shedding occurs in patches and lasts about 6 months each year (In the Komodo, this begins in September)
  • Tongue is long and narrow with a deep fork at its tip.
    • It does not move freely in the mouth, but retracts into a sheath.
    • It is partially supported by a complex structure of bone and cartilage called the hyoid apparatus.
    • Varanids are unique in using their tongues only as a sensory organ for locating prey and as a socialization tool. Other lizards use the tongue to manipulate food.

Coloration

  • Most adults are uniformly gray or clay-colored. Until the age of four they have much brighter, speckled skin. (Komodos of Flores retain brighter coloration)
  • There is little sexual dimorphism.
    • The flanks of adult females have more red than males.
    • Yellowish-green nose spots are more common in males
  • The light yellow tongue is species specific
    • V. salvator has a blue tongue
    • V. dumerili and V. grayi have pink tongues

Other Physical and Physiological Characteristics

Olfaction

  • Sense of smell extremely important in food detection.
    • Komodos can detect the scent of carrion from as far as 11 km.
    • Decomposition releases volatile oils - wind and size of prey are important factors
  • Each external nostril leads to a multi-chambered nasal capsule.
    • One of the chambers functions to excrete excess sodium. 
    • A pair of Jacobson's organs open into the roof of the mouth.
      • Scent particles are collected by the forked tongue and delivered to these sense organs which stimulate the brain to react.

Vision

  • Eyes are placed laterally and covered by two unequal lids.
  • Upper lid has little mobility.
  • Lower lid contains a cartilaginous plate which slides over surface of the eye

Hearing

  • The ear is important for maintaining balance as well as sound reception.
  • Behavior seems to be more scent than sound oriented

Respiration

  •  Varanid lungs are larger than most reptiles.
  • Take in relatively larger amounts of oxygen and their physiology produces a more efficient system of air circulation.
  • Breathing rate is regular and low but varanids can voluntarily hold their breath for long periods.

Circulation

  •  Varanids have a more complex heart structure and blood chemistry than other lizards.
  • This allows them to achieve intense activity without becoming exhausted.

Water/Salt Balance

  • Water makes up 70% of a lizard's body weight. (10% more than humans).
  • Varanid skin is covered with scales and contains no sweat glands.
  • Excess sodium is removed by a special salt-secreting glands in the nasal capsules (many lizards have them)

Skin Armor

komodo dragon skin

The chain mail-like scales covering a komodo dragon's body protect it from scapes and scratches.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Auffenberg (1981)
Ciofi (2004)
De Lisle (1996)
King & Green (1993)
Fry et al. (2006)
Fry et al. (2009)

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